1. Field of the Invention
The present invention relates to a plasma generation system. More particularly, the present invention relates to a plasma generation system that generates uniform high-density plasma.
2. Description of the Related Art
FIG. 1 schematically illustrates a structure of a conventional electron cyclotron resonance (ECR) plasma device.
Referring to FIG. 1, a shower plate 13 is installed in an upper portion inside a processing chamber 11. A gas for forming plasma is supplied into the processing chamber 11 over a substrate 10 via the shower plate 13. The substrate 10 is seated on a substrate holder 17. A radio frequency bias in a range of 100 kHz to 15 MHz is applied from a radio frequency power source 29 to the substrate holder 17 via a matching network 27.
An etching gas is supplied into the processing chamber 11 via a gas inlet 19. Electromagnetic waves having an ultra-high frequency in a range of 300 MHz to 1 GHz are generated in the radio frequency power source 29. The electromagnetic waves, which are controlled by a tuner 21, are introduced into the processing chamber 11 through a waveguide 23 and ionize the etching gas to create plasma. The electromagnetic waves are resonant in a predetermined mode by a quartz window 15 placed on an uppermost portion of the processing chamber 11.
For high-efficiency discharge, a solenoid coil 25 for generating a magnetic field is disposed around the processing chamber 11, and a coil current is controlled so that a magnetic field in a range of 0–360 Gauss is generated below the shower plate 10. Thus, ECR is generated, and high-density plasma having an electron density of 1011 electrons/cm3 is formed. Accordingly, the etching gas supplied into the processing chamber 11 via the gas inlet 19 is ionized to generate high-density plasma using electromagnetic waves and a magnetic field, thereby etching the substrate 10. The matching network 27 connected to the substrate holder 17 properly controls the temperature of the substrate 10 during an etching process and exhausts processed gas after the etching process using a pump 28 connected to the processing chamber 11.
In the conventional ECR plasma device as shown in FIG. 1, however, an entrance of the processing chamber 11, in which the quartz window 15 is placed, is narrow. Thus, when plasma etching is performed on a large-sized substrate, etching is performed only in a narrow area of the substrate and an etching profile becomes non-uniform. In an effort to etch a large-sized substrate, a conventional waveguide has been formed in a horn shape. In such an arrangement, however, microwaves passing through the waveguide diverge. Resultantly, plasma cannot be formed uniformly when a substrate has a large diameter.